1) Purchase the playfield plastic protector kits from pinbits.com
http://www.pinbits.com/index.php?main_page=product_info&cPath=13_88&products_id=625

2) Make sure to only use original rubbers on the posts. I made the mistake of installing Superband post sleeves and the ball was airborn all the time.

3) Take some photos of how you have it rubbered, especially the areas about the return/drain lanes on each side. When I first received my JM, it kept firing balls down the drains. Then after looking at some ipdb photos, I realized that it was rubbered wrong. The JM owner manual doesn't have a page dedicated to how to re-rubber the game, so be aware of this...

Hope this helps, These were the primary issues I had with mine.
-Brian